Incidence of new Salmonella serovar (S. ratchaburi) in Thailand.

Eighteen strains of Salmonella group E from stool samples were confirmed as Salmonella new serovar. 3, 10 : Z35 : 1, 6 by Centre International des Salmonella, Institut Pasteur, Paris, WHO Collaborating Center for Salmonella, Atlanta, USA and Salmonella-Zentrale Hygienischen Institut, Hamburg, Germany. The name of this new serovar was proposed as S. ratchaburi according to the place of its first isolation in Ratchaburi province. The new serovar of Salmonella was sensitive to many antimicrobial agents except streptomycin and erythromycin.

Significant increase in antibiotic resistance of Salmonella isolates from human beings and chicken meat in Thailand.

A total of 1715 Salmonella strains, including 600 S. enteritidis, 290 S.derby, 257 S. Weltevreden, 122 S. 1,4,5,12:i:-, 235 S. anatum, and 211 S. typhimurium, originating from 1308 human beings and 407 frozen chicken meat specimens collected in 1993 and 1994 were tested for antibiotic resistance. The disk diffusion method was used with nine disks of chloramphenicol, ceftriaxone, amikacin, kanamycin, ampicillin, sulfamethoxazole plus trimethoprim, nalidixic acid, gentamicin and ofloxacin. The resistance rates of human beings isolates in 1994 to ceftriaxone, amikacin and kanamycin were, respectively, 10.7%, 8.6%, 17.8% in S. enteritidis; 23.1%, 17.3% 33.0% in S. derby; 30.9%, 40.2%, 60.4% in S. weltevreden; 16.1%, 17.7%, 70.9% in S.1, 4, 5, 12:i:-; 25.7%, 21.6%, 24.7% in S. anatum; 18.9%, 15.7%, 37.8% in S. typhimurium, while those isolates in 1993 to the same three antibiotics were, respectively, 1.8%, 0.6%, 3.7% in S. enteritidis; 0.8%, 0%, 9.1% in S.derby; 1.8%, 2.7%, 10.8% in S. weltevreden; 3.8%, 0%, 23.0% in S.1, 4, 5, 12:i:-; 2.2%, 2.2%, 6.7% in S. anatum; 4.5%, 1.5%, 10.6% in S. typhimurium. It was shown that the resistance rates in 1994 were significantly higher than those in 1993. All isolates were susceptible to ofloxacin with the exception of one isolate.

Urea hydrolysis and suppressed production of thermostable direct hemolysin (TDH) by Vibrio parahaemolyticus associated with presence of TDH-related hemolysin genes.

A total of 18 strains of V. parahaemolyticus isolated from patients of past food poisoning cases occurring in Kanagawa Prefecture, Japan, were assayed for presence of the thermostable direct hemolysin (TDH) gene and the TDH-related hemolysin (TRH) genes (trh 1 and trh 2) with specific reference to their ability to hydrolyze urea and TDH production. A polymerase chain reaction assay revealed that all urea-hydrolyzing strains (9 strains) carried either trh 1 gene or trh 2 gene. The strains carrying the trh genes as well as the tdh gene produced TDH less by a factor of 4 to 16 than those carrying only the tdh gene, suggesting the expression of the tdh gene was suppressed by the presence of trh gene through a mechanism yet to be defined.